The presence of superoxide ions and related dioxygen species in zinc oxide—A structural characterization by <i>in situ</i> Raman spectroscopy

Zinc oxide exhibits unique properties that are reflected in a wide variety of applications, particularly the field transparent, conductive films. However, less attention has been paid to their color. Here, we present synthesis yellow-gray ZnO films at room temperature by femtosecond pulsed laser deposition. In situ Raman investigations these polycrystalline reveal existence superoxide ions, O2−, zinc oxide, which responsible for yellow color, and also detected powder single crystals. addition, further dioxygen species identified samples, including O2-molecule. The negative charge excess caused creates metallic as byproduct. Structural analysis reveals an unforced realization lattice. Density functional theory (DFT) calculations support assumed structural displacements well observed, unexpected bands. These results open up completely new insights into behavior ZnO.